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J. G. GITHENSi STEAM ROCK DRILL.

No. 312,348. Patented Feb. 17, 1885.

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III-I- IIIIIIIIIIII I! llllllllhl 1 lllllll H will l u, llluynn I iEIIIIIIIIHII' w. gm. c7 6% NITE STATES 'a'rnwr FHC JOSEPH C. GITHENS, OFN ElV YORK, N. Y., ASSIGNOR TO THE BAND DRILL COMPANY, OF SAME PLACE.

STEAM ROCK-DRILL.

SPECIFICATION forming part of Letters Patent No. 312,348, dated February17, 1885.

Application filed January 21, 1884. Renewed October 22, 1884. (Nomodel.)

IO tatory feed is effected by means of a spiral bar free to rotate inone direction only, and playing loosely in a nut in the end of thereciproeating pistonwhich carries the drill,whereby the stroke ofthepiston in one direction turns the spiral bar to a certain extent uponits 1011 gitudinal axis, thus imparting the rotary set to the bar,whichin its turn, during the stroke of the piston in the opposite direction,causes the piston to turn upon its longitudinal axis,

and to thus turn the drill to acorresponding extent.

The method heretofore employed for preventing the backward rotation ofthe spiral bar has been by the use of a spring detent pawl or pawlsacting upon a ratchet-wheel affixed to the journaled end of the spiralbar.

As the length of the working-stroke in engines of this character issubject to unavoidable variation, owing to variations in the extent ofthe longitudinal feed, which is governed manually, and the differencesin the resistance which the work opposes to the penetration of the tool,it not infrequently happens that the rotatory movement imparted to 3 5the spiral bar is of such extent as to carry the radial face or faces ofthe ratchet tooth or teeth to a point or points slightly in advance ofthe end or ends of the detent pawl or pawls which bear upon theperiphery of the ratchetwheel. In such cases the first effect of theopposite movement of the piston is to violently turn the spiral barbackward until it is brought up by the collision of the radial face orfaces of the ratchet tooth or teeth with the 5 end or ends of the detentpawl or pawls. The shock of this collision or backlash increases therapidity with which the parts wear and exposes the mechanism to theliability of breakage.

As the strokes of a rock-drill are made with great rapidity, it has beenfound necessary to employ strong springs to hold the detent pawl orpawls against the ratchet-Wheel. Thus the detent-pawls have acted asbrakes upon the ratchet-wheel, materially increasing 5 5 the amount ofpower required to effect the rotation of the spiral bar.

Owing to structuralpeculiarities ofthe rockdrill engines heretoforeemployed, the detentpawls have been applied on one side only of theratchetwheel, and the result of their action, therefore, has been tocause an excessive wearing of one side of thejournal of the spiral bar.

It is the object of the principal feature of my invention to prevent thepossibility of any backward movement of the spiral bar, what ever may bethe variations in thelength of the strokes of the piston, and theconsequent variations in the extent to which the spiral bar is turnedwhile having its rotary set imparted to it. I accomplish this object bythe inter position between the face of the wheel affixed to the spiralbar and the wall of a recess formed in the head of the cylinder in whichthe spiral bar is journaled of a gripping device or devices so arrangedas to bind and stop any backward rotation of the spiral bar, whileyielding freely to allow the forward rotation of the spiral bar. By thefree yielding of the gripping devices in one direction I am enabled toavoid the braking effect incident to the use of the spring detent-pawlsheretofore employed, and by the arrangement of several gripping devices,respectively, upon opposite sides of the wheel affixed to the spiral barthe bar is centralized and prevented from wearing its journal unevenly.

My invention is also applicable to steam rock-drills of the class inwhich the rotatory o feed is effected by means of a spirally-formedpiston-rod sliding through a rotating nut contained in a stationarychan1ber,and hence rotating in a fixed plane, in which case thegrippingdevicesareappliedbetweentheperiphery of the nut and the wall ofthe chamber in which the nut is contained.

The accompanying drawings, representing so much of a rock-drill engineas is necessary to exhibit my improvement, are as follows: 10c

Figure 1 is a central longitudinal section of a portion of the cylinder,showing the spiral bar and a portion of the piston in side elevation.Fig.2 is an end view, partlyin section, through the line X X on Fig. 1,showing the wheel affixed to the journaled end of the spiral bar,andseveral friction-rollers interposed between the teeth of the wheel andthe wall of a recess formed in the head of the cylinder. Fig. 3 is a topview of the cylinder.

The drawings show the cylinder A of a rock-drill engine and one of thesteam-passages ]3, leading from the valve-chest. The piston O has theusual piston-rod,O,afiixed to it at one end,and is longitudinallyrecessed at the opposite end to admit the spiral bar D, which fitsloosely, so that it can slide in the nut D, fastened in the outer end ofthe recess D in the piston. The spiral bar is provided with a journal,a, in the cylinder-head A, which is countersunk to form the cylindricalrecess a,for containing the wheel or hub d,affixed to the outer end ofthe spiral bar D. The periphery of the wheel or hub dis notched, and thebottoms of the notches present the cocentric faces d. or rolling stop,E, is deposited in each of the notches formed in the wheel or hub d. Thearrow Fin Fig. 2 indicates the direction in which the spiral bar is freeto rotate. An expanding spiral spring, 0, is seated in. the radial sideof each notch and presses the roller in front of it toward the narrowerpart of the space between the bottom of the notch and the wall of therecess a. On one side the roller bears upon the concentric wall of therecess a, and on the other side upon the eccentric face d,formingthebottom of the notch in which it is deposited. The diameter of the rolleris slightly less than the width of the space between the recess a andthe deepest part of the notch in which it is deposited. By the action ofthe expanding spring the roller is pressed forward, so that it bearsupon the bottom of the notch in which it is deposited and the wall ofthe recess a. Each roller, therefore, occupies a position which preventsany backward rotation of the spiral bar,while not interfering with theforward r0- tation of the bar in the direction indicated bythearrow,because by such rotation the roller is carried back into thewider part of the space between the bottom of the notch and the wall ofthe recess a.

In the drawings the wheel or huh (I of the spiral bar is represented ashaving four notches, between the bottoms of which and the wall of therecess a are interposed four frictionrollers, E, respectively. It willof course be understood that the number of notches in the hub and thenumber of friction-rollers employed may be either increased ordiminished, if desired, without departing from so much of the inventionas resides in the employment, in combination with a piston and spiralbar, of a frictional gripping device which binds A cylindricalfriction-roller between the hub of the spiral bar and the cylinder-headin such a way as to prevent any backward rotation of the spiral bar;and, further, it will be seen that the friction-rollers E do not opposeany appreciable resistance to the rotation of the spiral bar in thedesired direction, and that by arranging several friction-rollers uponopposite sides of the center of the spiral bar they serve to centralizethe bar in its journal. The cylinder-head A is provided with a cap, A",which is secured'in position by means of the usual longitudinal bolts, GG, extending through both heads of the cylinder, and provided with thenuts 9 q. A shorter bolt, H, provided with a nut, h, cooperates insecuring the cap A upon the head A, and is made hollow and provided withan internal screw-thread for engagement by the thread of the usualadjusting-bolt, by means of which the longitudinal feed is given to thecylinder.

No special description of the valve-gear is required, because it isimmaterial for the purposes of the present invention what kind ofvalve-gear is employed.

By the described method of eifecting and controlling the rotatory feedof the piston it will be seen that the extent of the rotatory feed ofthe piston, and consequently of the tool carried by the piston, is inall cases exactly equal to the extent to which the spiral bar is turnedduring that movement of the piston by means of which the rotatory set isimparted to the spiral bar. short stroke of the piston there will be aless extent of rotatory feed of the drill than there is when the pistonmakes a long stroke. This is important, because when the piston makes ashort stroke the force of the next succeeding blow is diminished, and itis therefore desirable that there should be a smaller extent of rotatoryfeed than in those cases where the piston makes a longer stroke. By myinvention, therefore, the rotatory feed of the drill is varied accordingto the variations in the length of the stroke of the piston. This resultis accomplished by making the extent of the rotatory feed dependent inall cases upon the length of the working-stroke of the piston-that is,the length of the stroke by which the tool is driven against the rock--because it is during the working-stroke of the piston that the rotatoryset is imparted to the spiral bar, the rotatory feed of the piston andtool being eflected during the return-stroke of the piston, at whichtime the spiral bar is held stationary.

In applying my invention to the class of steam rock-drills in which thepiston-rod is given a spiral form and slides through a nut looselycontained in a stationary chamber, the friction-rollers are deposited insuitablyshaped recesses between the nut and the wall of the chambercontaining the nut. In this application of my invention the spirally-,formed piston-rod is the equivalent of the It thus follows that in caseof a' spiral bar, and the nut contained in the sta tionary chamber isthe equivalent of the nut affixed to the piston; and thefriction-rollers acting on anut revolving in afixed plane, and engagingan endwise-reciprocating spiral piston-rod or spiral bar aflixed to thepiston, are the equivalents of the friction-rollers acting on the headof a spiral bar rotating in a fixed plane and engaging a nut aflixed to,and hence reciprocating with, the piston.

I claim as my invention 1. In a rock-drill or other analogous engine inwhich the piston is liable, when the machine is in operation, to makestrokes of variable length, and in which the rotatory feed of the pistonis effected by means of a spiral bar loosely engaging a nut formed in oraffixed to a longitudinally-rccessed piston, the combination of the saidspiral bar and piston with the herein-described mechanism for definitelyvarying the extent of the rotatory feed following difi'erentworking-strokes of the piston proportionately to differences in thelengths of such different working-strokes, the said mechanism consistingof a rolling stop or stops deposited in a recess or recesses between theinterior surface of a chamber formed in the head of the cylinder, and aportion of the head of the spiral bar, or of a wheel or collar affixedto the end of the spiral bar, and constituting the head thereof, and aspring or springs acting to force such rolling stop or stops,respectively, toward the narrower part or parts of the recess orrecesses containing 5 the said rolling stop or stops.

2. In a rock-drill or analogous engine, a longitudinally-recessed pistonand a spiral bar journaled in the cylinder-head and loosely engaging anut affixed to the piston, and provided near its journal with a wheel orhub having in its periphery a series of notches, the bottomsof whichpresent eccentric faces, in combination with a cylindrical recess formedin the head of the cylinder, and a series of friction-rollers deposited,respectively, in the notches of the said wheel or hub, and acorresponding series of springs supported in said wheel or hub, andexerting their tension in such a direction as to force the rollers,respectively, toward the narrower parts of the spaces between theconcentric wall of the recess and the eccentric faces which constitutethe bottoms of the notches.

3. In combination with the herein-described spiral bar and piston, twoor more rolling stops arranged upon opposite sides of the head of thespiral bar, and interposed between the head of the spiral bar and theinterior surface of a chamber formed within the head of the cylinder,for the purpose of centralizing the spiral bar and preventing it fromwearing its journal unevenly, substantially as described.

JOSEPH O. GITHENS.

Witnesses:

1%. O. Howns, M. L. ADAMS.

